1. Field of the Invention
This invention relates to a hinge unit to be suitably used for a portable electronic apparatus such as a portable telephone set, a portable computer or an electronic note book that comprises a main body and a swing member typically containing a microphone and secured to the main body by means of hinges such that the swing member may be folded on the main body for the convenience of storage when not in use and opened from the main body by a desired angle and held to the open position for use.
2. Prior Art
FIGS. 12A and 12B of the accompanying drawings schematically illustrate a known portable telephone set comprising a main body 1 and a swing member 2 linked to each other at an edge 1a of the main body 1 and the corresponding edge 2a of the swing member 2 by means of the paired hinges 3A, 3B of a hinge unit that connect the opposite ends 1b, 1b of the edge 1a to the corresponding knuckle-shaped opposite ends 2b, 2b of the edge 2a respectively.
With this arrangement, the swing member 2 can be folded on the main body 1 as indicated by solid lines in FIG. 12B for the convenience of storage and transportation and then be opened along the phantom lines to an operating position P so that the user can talk to the microphone arranged in the swing member 2 while he or she is holding the main body with a single hand (Japanese Patent Application Laid-Open No. 8-121462).
FIGS. 8A through 9C schematically illustrate the paired hinges 3A, 3B of the known hinge unit used in a portable telephone set. FIG. 8A is a partial plan view and FIG. 8B is a partial lateral view of the portable telephone set.
Each of the hinges 3A, 3B comprises a spring 4 and a cam shaft 5 pinched by the spring 4. As seen from FIGS. 9A and 9B, the cam shaft 5 is rotatable and unremovable fitted over a cylindrical bearing tube 5a whose base section 5a' is rigidly secured to the main body 1. The cam shaft 5 has a protruding section 5b having an enlarged cross section and extending axially and outwardly from the bearing port 1c of the main body 1 in the X-direction that is parallel to the edge 1a of the main body so that it is received by a bearing section 2c formed in the corresponding knuckle-shaped end 2b of the swing member 2.
The cam shaft also has a cam section 5c. The spring 4 fitted over the bearing tube 5a is rigidly secured relative to the edge 1a and has a pair of resilient tips 4a, 4a resiliently abutting the cam section 5c. As seen from FIGS. 9A through 9D, the cam section 5c has a pair of narrowly separated flat surfaces 5d, 5d for providing a stationary state and a pair of outwardly rounded surfaces 5e, 5e for providing an easily rotatable state.
Thus, with the paired hinges 3A, 3B arranged in a manner as described above, as the swing member 2 is turned from the closed position in FIG. 12B to the open position indicated by phantom lines, the cam section 5c of the cam shaft 5 of each of the hinges turns relative to the spring 4 and the flat surfaces 5d, 5d are caught by the resilient tip 4a, 4a to hold the swing member 4 in the open position, or operating position P, so that the user can operates the telephone set. When the swing member 2 is turned back to the closed position indicated by solid lines, the resilient tips 4a, 4a abut the respective rounded surfaces 5e, 5e of the cam section 5c to hold the swing member 2 to the open position.
Therefore, the telephone set is held either to an operating state or to a resting state by the hinges in a manner as described above. However, the hinges of the known hinge unit require an assembling operation for bringing the protruding section 5b of the main body 1 into engagement with the bearing section 2c of the swing member 2 as shown in FIG. 9B. More specifically, the swing member 2 of the telephone set is made of synthetic resin to make it deformable so that the bearing sections 2c, 2c of the swing member 2 may be brought into engagement with the respective protruding sections 5b, 5b of the main body 1 by forcibly separating the knuckle-shaped opposite ends 2b, 2b from each other.
Thus, considerable force have to be applied to the swing member to assemble the known portable telephone set. Such an assembling operation is time consuming and requires a considerable work load.
FIGS. 10 through 11E illustrate the hinges 3C, 3D of an improved known hinge unit proposed to eliminate the above identified problem.
While the known hinges have a configuration basically same as that of the hinges of FIGS. 8A through 9D, they provide an improvement as discussed below.
Each of the hinges 3C, 3D of the hinge unit comprises a spring 6 and a cam shaft 7 pinched by the spring 6. As seen from FIGS. 11A through 11E, the cam shaft 5 is rotatable and unremovable housed in a rectangular sleeve 8 rigidly secured to the main body 1. Additionally, the cam shaft 7 has a protruding section 7a having an enlarged cross section and extending axially and outwardly from the bearing port 8a of the rectangular sleeve 8 in the X-direction that is parallel to the edge 1a of the main body so that it is received by a bearing section 2c formed in the corresponding knuckle-shaped end 2b of the swing member 2.
Reference symbol 7b in FIGS. 11B and 11D denotes an antirelease edge of the cam shaft 7 for preventing the cam shaft 7 from being released from the rectangular sleeve 8 to move away rightward in FIGS. 11B and 11D as it abuts the bottom wall of the rectangular sleeve 8 where the bearing port 8a is arranged.
The cam shaft also has a cam section 5c as seen from FIG. 11E. The cam section 7c has a pair of narrowly separated flat surfaces 7d, 7d for providing a standstill state and a pair of outwardly rounded surfaces 7e, 7e for providing an easily rotatable state as in the case of the first known hinge unit.
The cam section 7c is fitted over a small diameter section 6b of a cylindrical bearing tube 6a of the spring 6 so that the cam shaft 7 is rotatable relative to the small diameter section 6b. Thus, the remaining large diameter section 6c of the cylindrical bearing tube 6a and the cam section 7c are axially located side by side in the X-direction. Additionally, as seen from FIGS. 11A and 11B, the large diameter section 6c has low lateral projections 6d, 6d that are engagedly received by respective grooves 8b, 8b formed on the inner wall of the rectangular sleeve 8 such that the cylindrical bearing tube 6a of the spring 6 is axially slidable in the X-direction by a given distance.
Still additionally, the spring 6 has a spring section 6e rigidly fitted to the small diameter section 6c and a pair of resilient tips 6f, 6f extending from the spring section 6e toward the cam section 7c and adapted to resiliently abut the flat surfaces 7d, 7d for providing a stationary state or the outwardly rounded surfaces 7e, 7e for providing an easily rotatable state of the cam section 7c as in the case of the first known hinge unit.
A coil spring 9 is arranged between the inner end of the large diameter section 6c of the spring 6 and the end wall members 8c, 8c of the rectangular sleeve 8 arrange opposite to the end where the bearing port 8a is located so that the cam shaft 7 is constantly urged outwardly, or rightward in FIGS. 11B and 11D, by the coil spring 9 by way of the spring 6 and hence the antirelease edge 7b of the cam shaft 7 is constantly held in abutment with the corresponding end of the rectangular sleeve 8.
With this arrangement, when the protruding section 7a protruding from the bearing port 1c of the main body 1 to an extreme position as indicated by phantom lines in FIG. 11D is pushed back, or leftward in FIG. 11D, by applying pressure thereto, the applied pressure is transmitted to the coil spring 9 by way of the cam shaft 7 and the cylindrical bearing tube 6a to force the cylindrical bearing tube to move in the X-direction as it is guided by the grooves 8b, 8b of the rectangular sleeve 8 until the protruding section 7 is moved to the opposite extreme position indicated by solid lines, when the coil spring 9 is completely compressed.
Thus, if the extent to which the coil spring is compressed is properly selected, the operation of bringing the protruding section 7a of the cam shaft 7 into engagement with the bearing section 2c of the swing member 2 can be performed quickly and easily simply by pushing back the protruding section 7a by means of a finger tip and then quickly pushing the corresponding knuckle-shaped end 2b of the swing member 2 toward the main body. Therefore, the second known hinge unit provide a significant advantages over the first known hinge unit.
However, each of the hinges of the second known hinge unit still requires the use of not only a pair of resilient tips 6f, 6f for the spring 6 to be held in abutment with the cam section 7c of the cam shaft 7 in order to keep the swing member 2 open relative to the main body 1 by a given angle and also in the closed position but a coil spring 9 in order to allow the protruding section 7a of the cam shaft 7 to restore the original position when it is released after having been pushed into the rectangular sleeve 8.
Additionally, the cylindrical bearing tube 6a rigidly holding the resilient tips 6f, 6f is divided into a large diameter section 6c and a small diameter section 6b which has to be fitted into the cam shaft 7 from an end thereof until the large diameter section 6c abuts the cam shaft 7 and the end wall members 8c, 8c of the rectangular sleeve 8 have to be bent after the completion of the assembling operation because they have been left unbent for easy assembling. Thus, the process of manufacturing and assembling such a hinge device is rather complicated and cumbersome.